Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 214,385	$ 167,088
Accounts receivable—oil and gas	30,798	25,615
Accounts receivable—related parties	36,823	34,848
Prepaid expenses and other current assets	2,639	1,506
Deferred tax asset	372	0
Short-term derivative instruments	863	664
Total current assets	285,880	229,721
Property and equipment:
Oil and natural gas properties, full-cost accounting, $872,113 and $626,295 excluded from amortization in 2013 and 2012, respectively	2,065,918	1,611,090
Other property and equipment	9,017	8,662
Accumulated depletion, depreciation, amortization and impairment	(717,007)	(665,884)
Property and equipment, net	1,357,928	953,868
Other assets:
Equity investments ($198,662 and $151,317 attributable to fair value option in 2013 and 2012, respectively)	438,864	381,484
Other assets	13,153	13,295
Total other assets	452,017	394,779
Total assets	2,095,825	1,578,368
Current liabilities:
Accounts payable and accrued liabilities	142,375	110,244
Asset retirement obligation—current	780	60
Short-term derivative instruments	1,839	10,442
Current maturities of long-term debt	154	150
Total current liabilities	145,148	120,896
Asset retirement obligation—long-term	13,231	13,215
Deferred tax liability	69,204	18,607
Long-term debt, net of current maturities	298,956	298,888
Other non-current liabilities	0	354
Total liabilities	526,539	451,960
Commitments and contingencies (Note 11)
Preferred stock, $.01 par value; 5,000,000 authorized, 30,000 authorized as redeemable 12% cumulative preferred stock, Series A; 0 issued and outstanding	0	0
Stockholders’ equity:
Common stock - $.01 par value, 100,000,000 authorized, 77,547,606 issued and outstanding in 2013 and 67,527,386 in 2012	775	674
Paid-in capital	1,398,188	1,036,245
Accumulated other comprehensive income (loss)	(10,982)	(3,429)
Retained earnings	181,305	92,918
Total stockholders’ equity	1,569,286	1,126,408
Total liabilities and stockholders’ equity	$ 2,095,825	$ 1,578,368